A conventional television comprises a microcomputer (or system controller) and several function control units which control various functions of the television. Examples of function control units may include a multi voice processor, a voice signal processor, a video signal processor, a teletext circuit, and a picture-in-picture circuit.
In order to instruct the television to perform a particular function, the microcomputer outputs a control signal to a selected function control unit via a corresponding control port, and the selected function control unit performs the corresponding function in accordance with the control signal. However, since the microcomputer cannot perform other functions while controlling the selected function control unit, the processing time of the microcomputer increases. Also, as the number of function control units increases, the amount of commands and instructions output from the microcomputer increases, and thus, the processing time of the microcomputer further rises. In addition, if the number of function control units is high, the wiring connections among the units and the microcomputer become more complex, and the amount of area on the printed circuit board and number of components required to implement the control units likewise increase. Furthermore, as the design of the above system becomes more difficult, the reliability of the system decreases.
In order to reduce the complexity and increase the reliability of the conventional television, the function control units and microcomputer may be connected via various buses. In particular, the microcomputer and the control units may be connected via bi-directional serial data and serial clock lines. Also, each function control unit may be assigned a specific address so that the microcomputer can instruct a particular function control unit to perform a particular function by outputting address and control data that correspond to the particular control unit. The above described system is referred to as an I2C bus system and the above described television is referred to as a bus-controlled television.
In order to produce and test the bus-controlled television mentioned above, a factory may be equipped with a bus control facility (e.g. a bus controller) 3 as shown in FIG. 1. Specifically, the bus control facility 3 and the bus-controlled television 1 are connected together via a bus connector. In order to ensure that the function control units of the television are operating properly, an operator varies the preset values for the television 1 by outputting a television test signal to the television 1 via a television test signal cable. Subsequently, a camera 2 detects the characters and other information displayed on the screen of the television 1 in response to the television test signal and outputs a resultant signal to the bus control facility 3. Subsequently, if the displayed information is improper, the operator must adjust the preset values until the characters displayed by the television 1 are correct. However, since the adjustment procedure illustrated above is not automated, it is time consuming and thus, increases the time to manufacture and test the television 1.